1. Field of the Invention
The present invention relates to a toner transport apparatus, and more particularly, to a toner transport apparatus that transports toner particles laterally first and then downward and an image forming apparatus to which the same is applied.
2. Description of the Related Art
An image forming apparatus, such as a printer, is provided with an image forming portion including a photoconductive drum and a developing device, a sheet feeding portion that feeds recording sheets to the image forming portion, a sheet carrying portion that carries recording sheets bearing formed images, a fixing portion that fixes toner images on recording sheets, and a sheet discharge portion where recording sheets onto which are fixed the toner images are discharged.
In the image forming apparatus thus configured, an electrostatic latent image is formed on the surface of the photoconductive drum according to image information, and after the electrostatic latent image is developed to a toner image by the developing device, the developed toner image is transferred onto a recording sheet. In the case of a full-color image forming apparatus, such as a color printer, four developing devices respectively storing developing agents in cyan, magenta, yellow, and black are provided, and development in these four colors, cyan, magenta, yellow, and black, is performed by the corresponding developing devices.
With such a full-color image forming apparatus, personal use has been increasing in recent years, and so is a need to reduce the apparatus both in size and cost. To meet this need, a compact image forming apparatus adopting a rotary developing apparatus is now being developed. In this rotary developing apparatus, developing devices respectively corresponding to toner particles in plural colors are supported on a rotary frame body.
In order to achieve a reduction of the rotary frame body in size as well as a reduction in load when driving the rotary frame body, the rotary developing apparatus adopts a method by which a toner container storing toner particles is provided apart from the rotary frame body so as to replenish the developing devices on the rotary frame body with toner particles from the outside toner container (for example, JP-A-10-198149).
For an image forming apparatus adopting the method of replenishing the developing devices with toner particles from the outside toner container, there is a need for a toner transport apparatus that transports toner particles from the toner container to the developing devices. When toner particles are replenished, the replenishing efficiency of toner particles is enhanced by inserting a toner replenishing pipe into the developing devices from above. It is therefore configured in such a manner that the toner replenishing pipe transports toner particles in a longitudinal direction. Meanwhile, it is often difficult to place the toner container above the toner replenishing pipe due to limitations of space within the apparatus. Accordingly, there arises a need to provide a transport apparatus that transports toner particles in a lateral direction between the toner container and the toner replenishing pipe.
As has been described, a transport apparatus that transports toner particles in a lateral direction and another transport apparatus that transports toner particles in a longitudinal direction are necessary between the toner container and the developing devices. In this case, in the event that toner particles are not delivered in a satisfactory manner at transition between lateral transportation and longitudinal transportation, toner particles may possibly build up at the transition point.